An effective use of despreading in estimating the incoming time or direction of a spread spectrum signal may result in an increase in the number of samples, and lead to an increase in the amount of calculation. An example is an estimation of multipath in a GPS (Global Positioning System) signal. U.S. Patent Publication Number 2004/0208236, for example, discloses a multipath estimation directed to reduce the number of samples by extracting and analyzing the waveform of a portion of a spreading sequence (i.e., a code) where a symbol changes to an inverted symbol (hereinafter, referred to as a “portion of symbol inversion”), like Vision Correlator (Registered Trademark).